Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 15 of 15 for “"Pollen--Dispersal"”.
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Pollen study in Castanea dentata and C. mollissima
… the direction and distance of C. dentata pollen dispersal. The study of C. dentata pollen dispersal patterns was set up at an isolated orchard in Cleveland, Tennessee. Pollen collectors were placed at 13 locations in an array 15.2, 30.4, 46 and 61 meters north, northeast and east from the …
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Estimating source area of pollen and pollen productivity in the cultural landscapes of southern Sweden - developing a palynological tool for quantifying past plant cover
Fossil pollen records retrieved from peat and lake sediments have great potential for quantifying past plant cover. This thesis is a contribution to the development of a palynological interpretation tool for reconstructing past cultural landscapes in terms of plant abundance and distribution. The …
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Dioecious Plants: Evolution And Sex Ratio And Asepen Decline
… looked at the role incestuous matings, seed and pollen dispersal patterns, and compensation play in the evolution of this sexual system using two theoretical models we developed. Finally, we studied aspen populations in the Midwest to determine how climate variables affect growth and decline. We …
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The effects of population size on agathosma collina (rutaceae) and its conservation implications
… gene flow studies were carried out using pollen dispersal and seed dispersal. Although direct estimates of gene flow proved difficult to obtain, these studies indicated that gene flow was limited. Neighbourhood area resulting from estimates of pollen dispersal distances was only 2.12m² …
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Evaluation of Masculinization Treatments to Produce Feminized Hemp Seed (Cannabis sativa L.)
… with STS exhibited superior masculinization and pollen dispersal compared to plants treated with AVG, CBN or 1-MCP. Only plants treated with STS or AVG produced pollen in sufficient quantities for collection. This pollen was assayed for germination potential initially and after storage for up to …
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Aeropalynology in North London
This study investigates the abundance and dispersal of pollen in an urban area with a view to making accurate predictions of daily pollen counts. Two-hourly pollen counts of more than 60 different pollen types have been recorded over four complete growing seasons in the heavily urbanized area of …
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Reproduction and establishment of two endangered African cedars, Widdringtonia cedarbergensis and Widdringtonia whytei
… that a reduction in population density may limit pollen dispersal, reduce seed viability and increase self-pollination rates, causing an inbreeding depression, resulting in less fit offspring. Based on this research, I hypothesise that pollen transfer in Widdringtonia is distance-dependant and …
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Study on the dispersion of particles at a fluid-liquid interface and its application in hydrophilous pollination
… the mechanisms of two-dimensional aquatic pollen dispersal, known as hydrophily is also studied and presented here. The aquatic pollination has evolved in several genera of aquatic plants, including Halodule, Halophila, Lepilaena, and Ruppia. Ruppia maritima, which is native to salt and …
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The effects of clonal reproduction on population demography, genetic structure, and mating pattern of <i>Dicentra canadensis</i>
… Clustering of clones can reduce the frequency of pollen transfer between genets if pollinators tend to forage on nearby plants. In extreme cases, clustering of clones may prevent sexual reproduction, especially in plants that require mating between different genotypes to produce seeds. The …
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Bioaerosol Dispersal Across Scales: Regional Patterns, Field Study, and Model Evaluation
Bioaerosols--including seeds, pollen, fungal spores, bacteria, and viruses--are fundamental agents connecting atmospheric processes to agriculture, ecosystem function, and human and animal health. This dissertation uses Lagrangian stochastic (LS) models to simulate how these particles travel and …
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A landscape approach to forecasting climate change impacts on geographic ranges and phenologies of plants in the Washington Cascades
… elevation ranges, decreasing the potential for pollen dispersal between meadows. Because 2015 conditions were similar to those expected by the late 21st century under unabated climate change (early low-elevation snow melt, warm spring temperatures), this raises the possibility that climate …
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Population genetics of South African Protea L. (Proteaceae) species associated with various pollinator guilds
… affect population connectivity and gene dispersal. This was done by comparing indirect estimates of gene flow in the therophilous, P. amplexicaulis, and ornithophilous, P. laurifolia. These estimates included population differentiation (G”st) between subpopulations and spatial genetic …
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A pollen analytical investigation of Holocene palaeoenvironments at Lake Tyrrell, semi-arid Northwestern Victoria, Australia
This thesis presents a pollen analytical reconstruction of mallee vegetation history in the vicinity of Lake Tyrrell, a large active salt lake in semi-arid northwestern Victoria. The project combined studies of the modern pollen rain, pollen depositional processes and sedimentological …
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A pollen analytical investigation of Holocene palaeoenvironments at Lake Tyrrell, semi-arid Northwestern Victoria, Australia
This thesis presents a pollen analytical reconstruction of mallee vegetation history in the vicinity of Lake Tyrrell, a large active salt lake in semi-arid northwestern Victoria. The project combined studies of the modern pollen rain, pollen depositional processes and sedimentological …
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Estudio de las pautas de reproducción de Quercus ilex L. y Q. suber L. mediante marcadores moleculares
… information regarding the genetic structure and pollen dispersal in holm and cork oaks, which can be used for the sustainable management of the dehesas. The regeneration of the dehesas has been genetically analyzed for the first time. Nuclear microsatellites (nSSR) have been transferred to these …